I posted about a bad vibration I had at speed with my 2.7t A6 after a RS4 clutch install.

I finally found a loose fastener from the half shaft to the trans. Not sure if I did not tighten it or it lost torque.

For those chasing mystery problems or for anyone taking off their half shafts I'd seriously consider buying new bolts.

The current bolts on my 2000 use a much smaller triple square and it was difficult to get torque on them without stripping them. I think this lead to a lot of my issues.

I purchased a single new bolt from Audi to replace the loose one with a now stripped head and the new bolt has a much bigger head on it.

I didn't look at my triple squares but I'd say the original was a 10 and the new one is a 12/14.

They hold do not strip out so easily like the old ones and I replaced all 12 after doing the first one and seeing a massive improvement in my shake problem. I wasn't hoping they were not going to strip when I got near 65ft lbs.

The bolt that originally came with it was way too small for that much torque and Audi must have realized it since they have since changed the design.